Flexible mandrel



0a. 1, 1963 'H. M. SPATES v 3,105,538

FLEXIBLE MANDREL Filed Aug. 8, 1960 I h zl A92 20 Fig.4 y 0 23 3| INVENTOR. Henry M Spies ATTORNEY 3,105,538 FLEXIBLE MANDREL Henry M. Spates, 6667 E. Dorado Ave, Englewood, Colo. Filed Aug. 8, 1960, Ser. No. 48,113 1 Claim. (Cl. 153-63) This invention relates to the art and practice of bending tubular lengths of pipe and tubing, and analogous conventional material products, resistant to fiexure, and more particularly to the art and practice of bending thin- Walled, metallic tubing of moderate diametric size, and has as an object to provide a novel and improved facility useful to ease and to expedite the production of undeformed bends at desired locations in lengths of such material.

A further object of the invention is to provide a novel and improved flexible mandrel interiorly coactable with a length of tubular material to support the latter against collapse, or transverse deformation, at the zone of a bend in the length thereof.

A further object of the invention is to provide a novel and improved flexible mandrel operable to sustain tubular material against transverse deformation at the zone and during development of a bend in the material length and to correct any irregularities in the completed bend as an incident of mandrel retraction therefrom.

A further object of the invention is to provide a novel and improved flexible mandrel useful in the bending of tubular material that is characterized by long practical life and expeditious rehabilitation of its elements.

A further object of the invention is to provide a novel and improved construction and operative correlation of elements constituting a flexible mandrel useful in the bending of tubular material.

A further object of the invention is to provide a novel and improved construction and supplementing interrelation of elements constituting a flexible mandrel useful in the bending of tubular material that is distinguished by facility of component assembly, disassembly, and replacement, dependable strength, amenability to high exterior polish, and resistance to Wear and deformation.

With the foregoing and other objects in view, my invention consists in the construction, arrangement, and operative combination of elements hereinafter set forth, pointed out in my claim, and illustrated by the accompanying drawing, in Which FIGURE 1 is a side elevation of a practical embodiment of the improvement as organized ready for use, one end portion of the illustrated structure being broken away to better disclose interior arrangements and relatively-adjustable elements at the other end of the disclosed organization being indicated in alternative disposition by broken lines.

FIGURE 2 is a longitudinal section on a relativelyenlarged scale substantially axially through and approximately on the indicated line 2-2 of the major righthand portion of the organization according to FIG- URE 1.

FIGURE 3 is a section similar and at right angles to the showing of FIGURE 2 taken approximately on the indicated line 3-3 of the last-named view,

FIGURE 4 is a transverse section taken substantially on the indicated line 44 of FIGURE 3.

FIGURE 5 is a transverse section taken substantially on the indicated line 55 of FIGURE 3.

FIGURE 6 is a side elevation similar and on an enlarged scale relative to the right-hand portion of FIG- URE 1 illustrating a modified construction within the contemplation of the invention.

In the industrial arts there is frequent and recurrent aired rates Patent occasion for the bending of tubing to arcs of relatively small radius and or" right-angular extent. Various considerations often favor bending of tubular material without application of heat to inevitable deformation of transverse aspects of the material at the bend portion when tubular wall interior support is absent, to correct which condition various constructions of facilities, commonly termed flexible mandrels, have been devise and used, but the hitherto known such mandrels having evidenced certain deficiencies and inadequacies, the instant invention is directed to the provision of a novel and improved such device characterized by enhanced utility, practicality, and efliciency.

Organized in accordance with and to give effect to the principles of the invention, the improvement, as illustrated by the drawing, is a unitary, separable assembly of elements and features correlated with and for manipulation by a rigid, cylindrical stem having an inner end portion it of a length approximately twice a diarnetric size adapted for conformable engagement and free axial reciprocation interiorly of the tubular material length to be bent, and an integral, coaxial, outer end portion '11 of slightly-reduced diameter extending from and in shouldered relation with the portion 19. The free end of the stem portion 11 is socketed witha coaxial, internally-threaded bore 12 Wherethrough the stem may be connected to actuating means responsive to applied power, manual or other, to effect axial shift of the stem relative to and interiorly of a tubular length thereby engaged, and a hole l3 diametrically traverses the stem portion 11 adjacent its junction with the portion 10 for the removable and replaceable accommodation of an anchor pin, or hm, not shown, through Which forces may be applied to act axially of the stem. The end of the stem portion ill remote from the portion 11 is finished to a semi-circular plane 14 perpendicular to the stem axis which is complementary to an inclined end plane 15 in an obtuse angular relationship characterized by a line of plane intersection diametric of the stem and desirably parallel to the axis of the hole 33, through which planes and their line of intersection a cylindrical socket 16 is entered coaxially of the stem. *Inwardly from its terminal planes 14 and 15, the stem portion lib is diametrically apertured for the reception and operative accommodation of a removable and replaceable stud 17 thereby disposed to diametrically traverse the socket 16 with the stud axis desirably parallel to the line of plane 14 and 15 intersection and ends of the stud retracted away from obtrusion through the exterior cylindrical surface of the stem portion 1G, as by means of a countersunk disposition of the stud head and a threaded coaction of the lesser end of the stud with its accommodating aperture. respect significant to efficient realization of its intended functions, the stem unit at the end of its portion 10 determined by the plane 14 is slightly contracted and exteriorly relieved peripherally of said plane 14 to present at the stern side remote from the inclined end plane 15 an arcuate fillet 1S tangential to the cylindrical Wall of the stern portion it on a radius centered in a projection of the plane 15 at the side of the stem remote from the plane 14.

The flexible portion of the improved mandrel is comprised of tWo or more circular blocks 19 and a terminal block 29 separably interlinked for relative articulation and detachably coupled to the stem unit above described for adjustment between coaxial alignment with the stem unit and right-angular departure therefrom in a plane perpendicular to the axis of the stud '17. The blocks 19 are identical in a number determined by their like axial dimension and the angularity of the inclined plane 15 as correlated with coactable inclined plane areas In a further I a of the blocks to be appropriate for the desired range of angular adjustment characterizing the mandrel, and each of said blocks 19 of the organization according to FIGURES 1-,5, inclusive, is circular to a maximum diameter the same as that of the stem portion 16, is symmetrical with respect to the median diametric plane of its maximum diameter, is peripherally arcuate perpendicular to said median diametric plane to a radius the same as that of the fillet i8, and is of an operativelyappropriate axial length established by semi-circular end planes 21 identical with the end plane 14 perpendicular to the block axis in registration as opposite end faces of the block. The planes 21 of the blocks .19 terminate on registered diameters of the associated block which mark the lines of intersection with said planes of inclined block end flat areas 22 similarly convergent away from their lines of intersection in an obtuse angular relationship with their respective planes 21 the same as that characterizing the intersecting planes 14 and 15 above described, and each of said blocks 19 is centrally and symmetrically broached to provide a preferablysquare hole 23 axially therethrough. In a circularity, peripheral convexity, axial dimension, and accommodation of a hole 23 the same as obtains for the blocks 19, the terminal block 29 is provided with a semi-circular end plane 21 and angularly-intersecting fiat end area 22 corresponding to the equivalent features of the blocks 19 on but one of its ends and differs from the blocks 19 in that at its other end its axial length is determined by a full-circle, diametric plane 24 perpendicular to the block axis.

With the stem and block components of the improvement constructed as shown and described and the holes 23 arranged tointersect the blocks with one pair of the hole side Walls parallel to the lines of plane 21 and area 22 intersection of the associated block, the assembly thereof is operatively completed by means of a unique intercoupling arrangement evidencing important advantages of structure and function. Primary to the operative interrelation of the stem and block components is a cylindrical bolt 25 telescopically receivable with a sliding fit within the socket 16 of the stem portion 110 which is diametrically traversed by a hole for the reception of the stud 17 whereby said bolt is detachably secured within and held against rotational or axial movement relative to the socket. The bolt '25 is of an axial length such as to project exteriorly from the socket when secured in the latter by the stud 17 and is formed at its end adapted to so project as a tongue 26 having spacedly-parallel fiat sides perpendicular to the axis of the stud 17 in shouldered relation with and fully transverse of the bolt. The free end of the tongue 26 is circularly arcuate to a center coincident with the diametric line marking intersection of the planes 14 and 15 and is interrupted by a correspondingly-centered hole consequently axially parallel to the stud 17, which hole is adapted to operatively mount a cylindrical pin 27 of a length receivable within the lateral open span of the hole 23 through one of the blocks 19, which pin 27 is consequently disposed with its axis coincident with the line of intersection of the planes 14 and 15 when the bolt 25 is secured by means of the stud 17 interiorly of the socket 16. Ends of the pin 27 symmetrically projecting from the opposite flat faces of the tongue 26 engage through and pivotally mount apertured and concentrically-rounded ends of like, flat links 28 slidably width-receivable through the hole 23 of a block 19 in a thickness supplementing that of the tongue 26 susceptible of sliding accommodation within such hole 23, which links 28 are determined as to length by convex ends rounded in concentric relation with holes accommodative of a second pin 27 thereby disposed with its axis parallel to the pin 27 engaged through the tongue 26 and at a spacing from the axis of the latter equal to the axial dimension of a block 19, whereby the axes of said spaced pins 27 are arranged to register in coincidence with the diametric lines marking intersection of the planes 21 and areas 22 oppositely terminating a block 19 wherethrough the paired links 23 are slidably received. The second pin 27 coupling the ends of the links 28 remote from the tongue 26 engages through and pivotally mounts one apertured, rounded end of a link 29 identical with either of said links 28 save as to a relatively-greater thickness corresponding with the like dimension of the tongue 26 adapting said link 29 for embracement between the links 28 on the second pin 27 in spaced opposition to the end of said tongue, and the other, rounded end of the link 29 pivotally co acts with a third pin '27 thereby positioned parallel to the second pin 27 at a spacing therefrom the same as the spacing between the first and second pins 27 for consequent coincident registration of the axis of said third pin 27 with the diametric line of plane 21 and area 22 intersection characterizing a block 19 engaged over the link 29 to registration of its other such line of intersection with the axis of the second pin 27. Ends of the third pin 27 symmetrically projecting from 0ppo site sides of the link 29 engage through corresponding end apertures of and pivotally mount a second pair of links 28, identical with the like-designated elements above described, to center the registered apertures of the other link ends in the end plane 24 of the terminal block 20 when the latter is slidably engaged over said second pair of the links 28 with its line of plane 21 and area 22 intersection coincident with the axis of the third pin 27, and a retaining pin 30 correspondingly and diametrically end-notched in a length exceeding that of the pins 27 to provide registered, oppositely-directed, semi-cylindrical terminals 31 in outward extension from an intermediate semi-cylindrical portion length-receivable within the hole 23 of the block 20 traverses the apertures at the ends of the second pair of links 28 remote from the third pin 27 with the flat, diametric faces of said terminals 31 overlying and in contact with adjacent areas of the plane 24 of the block 20 as stops limiting displacement of said block along the second pair of links 28 in a direction away from the bolt 25.

As should be readily apparent, the construction and operative correlation of components and elements illus-. trated and hereinabove described contribute importantly to facility and economy of their production, practicality and utility of the mandrel unit therefrom comprised, and convenience of simple mandrel unit assembly and disassembly. With the requisite components and elements at hand, assembly of the unit is easily accomplished through pivotal interconnection of the bolt tongue 26, links 28, and link 29 by means of the three pins 27 slidably entered through the appropriately-registered apertures thereof whereafter, prior to insertion of the retaining pin 30 the blocks 19 and 20 are slidably engaged over the link assembly in registered juxtaposition of their transverse planes 21 in a manner to dispose the plane 24 of the block 20 at the end of the block series remote from the bolt 25, the mounted blocks are moved along the interconnected links toward said bolt to uncover the apertures at the free end of the second pair of links 28, the pin 30 is then inserted through the uncovered apertures and rotated to present the flat faces of its terminals 31 in opposition to the plane 24 of the terminal block 29, the mounted blocks thereafter are shifted to contact of said plane 24 with the flat faces of the terminals 31 and to interengagement of their opposed planes 21, in which relationship the pins 27 and the pin 30 are confined by walls of the block holes 23 against axial displacement disruptive of the link interconnections thereby established and the axes of the several pins 27 are registered in coincidence with the diametric lines of block end surface intersection contiguous thereto, whereafter the bolt 25 at one end of the link and block assembly is entered in its socket 16 and therein secured by the stud 17 in such relation with the stern portion 16 as is efiective to contactingly register the stem portion end plane 14 and the several block end planes 21 is an obvious and appropriate sequence. Manifestly, retraction of the stud 17 out of engagement with the bolt 25 releases the link and block assembly from the stem for such disassembly of the links and blocks in a reversal of the procedure above described as may be requisite to accomplish desired adjustment, conditioning, or replacement of any of the elements comprised in the assembly.

Use and practical operation of the mandrel. unit constructed and organized as shown and described require little elaboration. Susceptible of coaxial alignment with the associated stern when the several planes 14 and 21 are interengaged as shown by full lines in FIGURE 1, the blocks 19 and 29 are free to articulate on the spaced axes of the three pins 27 and to hinge at their colinearlyjuxtaposed diametric lines of end plane intersection in a progressive angular deviation away from coaxial alignment with the stem limited and determined by interengagement of the inclined, adjacently-opposed plane and area features and 22 of the associated elements to an arc desirably of right-angular extent convexly conformed to the axial peripheral contour of the block elements, as indicated by the broken line showing of FIG- URE 1. Insertable and reciprocable longitudinally within a straight tubular length of conformable size, the improved mandrel unit of the invention may be manipulated by any suitable means engaged with the threaded bore 12 at the free end of the stem section 11 and thereby positioned longitudinally of the associated tubular length at the zone of a desired bend therein with the axes of the mandrel pins 27 perpendicular to the plane of the bend, whereby to oppose the articulated blocks 19 and 21) to the influences tending to transversely deform the tubular material during the bending operation without appreciable resistance to the latter. Upon completion of the bend, retractive forces applied through the manipulating means attached to the mandrel unit withdraw the latter from the bent tubular length with truing and smoothing eifect upon the bend therein occcasioned by successive translation therethrough of the angularlydisplaced blocks 19 and in their return to coaxial alignment With the stem; the axial peripheral contour of said blocks coincident with the convex outline of a right-angular bend and the angular separation of the block and stem end planes obtaining during angular displacement of the blocks facilitating and enhancing bendtruing and bend-smoothing effects incident to translation of the maximum diameter planes of said blocks through the bend during retraction of the mandrel.

The modification according to FIGURE 6 is structurally equivalent to and functionally identical with that hereinabove described and difiers from the organization according to FIGURES 1-5, inclusive, only in that the blocks 19 of the first-described arrangement are replaced by blocks 19' of slightly different maximum diameters less than that of the stem portion 10 and the block 20 arranged in a progression of their maximum diameters with the smallest of the blocks adjacent the end of the stem portion 10. In all respects other than their maximum diameters the same as the blocks 19, the blocks 19 of the modified organization are amenable to production, assembly, disassembly, use and operation precisely as above explained, and are provided in their variation of maximum diameter and series arrangement to accommodate, when practical considerations warrant,

some transverse deformity at the bend zone of tubular I material during the bending operation, it being apparent that slight constriction of the material may occur in the clearances established about the lesser circumferences of the blocks 19, and to provide for correction of such deformities as may occur as the blocks of progressivelyincreased diameters traverse the bend during retraction of the mandrel unit terminated by the block 29 of maximum size.

It is noteworthy, and of significant practical importance, that the construction and organization of the improved mandrel provide in the blocks 19, 19' and 2% subject to major stress in use a maximum mass of solid, thick-walled material in a form amenable to effective tempering and hardening adapted to receive and retain a high surface polish which promotes the utility of the blocks as bend-truing and bend-smoothing agents. A further advantage of the construction and organization of the mandrel of the invention is found in the elimination of all tensile forces acting upon and tending to damage the block elements subject to major stress through the provision of a block linkage and intercoupling reactive to the forces incident to mandrel retraction to compress the blocks in response to retractive force transmitted through the bolts, links, and pins for action against the end face 24 of the terminal block 20; the tensions incident to mandrel. retraction being localized in the bolt, tongue, links and pins which may be of trough, strong metal other than that requisite to withstand the influences to which the blocks are subject.

Since changes, variations, and modifications in the form, construction, and arrangement of the elements shown and described may be had without departing from the spirit of my invention, I wish to be understood as being limited solely by the scope of the appended claim, rather than by any details of the illustrative showing and foregoing description.

I claim as my invention:

In a flexible mandrel having a cylindrical terminal stem and a succession of annular blocks adapted for registered, abutting coaction in coaxial extension from one end of said stern and for relative articulation on contactingly-registered diameters to arcuate deviation from the stem axis, the individual blocks alike transversely circular and peripherally convex in radial planes and of different diameters in one instance equal to and otherwise not exceeding the diameter of the stem and comprising said succession in a progressive correlation of their diametric sizes such as to convergently taper the elfective area of the succession from a terminal block diametrically equal to the stem at the end of the succession remote from stem and to a block of least diameter at the end of the succession adjacent the stem, the said individual blocks being alike formed with central apertures adapted to register as a smooth-walled slideway of uniform transverse area axially of and entirely through the block succession, and the end of the stem adjoining the succession being formed with a socket opening coaxially through the circular end face thereof in alignment with said slideway, a pivotally-intercoupled link assembly accommodated in said slideway for unrestrained reciprocation relative to the blocks thereby traversed, means for detachably aflixing one end of said link assembly to the socketed end of the stem, and retainer means at and extending laterally from the other end of said link assembly disposed to engage the exposed circular face of the diametrically-greatest block terminating the succession and thereby secure the blocks of the succession against separation, whereby attachment of the one end of the link assembly to the stem serves to compact and hold the individual blocks of the succession in operative interengagement of their registered diameters.

References Cited in the file of this patent UNITED STATES PATENTS 1,654,697 Mueller et al Ian.- 3, 1928 1,683,573 Mueller et al. Sept. 4, 1928 2,345,443 Aiken Mar. 28, 1944 2,451,717 Check Oct. 19, 1948 2,962,077 Condifi Nov. 29, 1960 

